Unlike smoking, conventional smokeless tobacco (ST) use (moist snuff, known as dip and chewing tobacco) among US high school students is much higher among males (13%) than females (2%) and is especially high in rural areas. Among rural high school male athletes and smokers, smokeless tobacco use ranges from 18% to 42%. In 2005, ST manufacturers spent over $250M on marketing, including new ST products such as dissolvable films, compressed tobacco (e.g. tablets and toothpick-like sticks), and snus products, modeled after Swedish snus, a relatively low-tobacco carcinogen and high-nicotine-content moist snuff. Between 2006 and 2008, Reynolds American and Philip Morris/Altria bought ST companies and started aggressively promoting new ST line extensions of their flagship Camel and Marlboro cigarette brands (e.g. Camel Snus, Camel Orbs and Camel Sticks, and Marlboro Snus). Expanded promotion of conventional, new, and emerging ST products may encourage increased ST use and dual use with cigarettes among adolescent males. No data exist on the addictive potential or nicotine and carcinogen exposure in adolescents using new ST products alone, or in dual use with cigarettes. We propose a clustered longitudinal observational study of adolescent male athletes to better understand cognitive and social determinants of conventional and new ST product use, their dual use with cigarettes, and the impact of exposure to ST marketing and anti-tobacco messages (e.g. graphic warning labels) on risk and benefit perceptions, change in ST use status (experimentation, initiation, relapse, switching, and cessation) and actual exposure to nicotine and carcinogens over time in rural high school males. Specifically, we propose to 1) measure patterns and determinants of conventional and new ST product use and dual use with cigarettes over time; 2) measure tobacco marketing and anti-tobacco message exposure and their association with ST use, perceived risks and benefits of use, and future expectations of conventional and new ST product use and dual use with cigarettes over time; 3) evaluate nicotine and carcinogen exposure and their association with the rate of nicotine metabolism in conventional and new ST product users, and users of multiple forms of tobacco; and 4) identify factors in addition to product type and brand that predict nicotine and carcinogen exposure (e.g. measures of risk and benefit perception and nicotine metabolism rate).